The present invention relates generally to production techniques of radio-engineering equipment, and more specifically to devices for fusion of electrodeposited coatings of printed-circuit boards.
The invention can find most utility when applied for fusion of electrodeposited coatings on printed-circuit boards used in radio-engineering circuits. In addition, the invention is applicable for fusion of electroplating on flat structural components of equipment subject to soldering during subsequent assembling.
Known in the present state of the art is a device for fusion electrodeposited coatings of boards, comprising a bath with a heat-transfer agent, a mechanism for establishing a flow of the heat-transfer agent, a means for imparting a desired direction to the flow of the heat-transfer agent, and a mechanism for traversing the boards being handled through said means.
The means for imparting a desired direction to the flow of the heat-transfer agent is made as a pair of intercommunicating pipings arranged horizontally one above the other and having the heat-transfer agent outlet fittings facing each other.
The mechanism for establishing a flow of the heat-transfer agent in the bath is essentially a pump with an impeller and a drive electric motor.
The mechanism for traversing the boards being handled is made as a screen conveyer having stops for the boards being handled, the top (carrying) strand of the conveyer passing between said pipings, while its bottom (return) strand runs underneath the bath.
The board on which the electroplating is to be fused is put onto the conveyer, having preliminarily adjusted the stops thereon to suit the length of the board being handled. When carried by the conveyer the board is transferred into the zone of action of the heat-transfer agent, which is pumped from the bath into the piping. While leaving the outlet fittings the heat-transfer agent preheated in the bath, is splashed over the top and bottom board surfaces as along the direction of the board run on the conveyer, thus fusing the electroplating on the board.
However, the construction of the device described above fails to provide high-quality fusion, inasmuch as it cannot stabilize the time-dependent temperature characteristics of the heat-transfer agent involved in treatment of boards.
Splashing of the heat-transfer agent over the board surface during the board treatment results in rapid cooling of the heat-transfer agent, so that the operation of the device is to be stopped from time to time for the heat-transfer agent to acquire a preset temperature in the bath.
In the course of operation the heat-transfer agent is liable to be vigorously oxidized by the atmospheric oxygen, while the crystallization process is not stabilized due to the fact that the construction of the device fails to prevent the heat-transfer agent from running onto the already treated board.
In addition, to proceed to handling the boards of another type-and-size also involves stopping of the device for readjustment of the stops on the conveyer.
Apart from the disadvantages mentioned above the construction of the device is not suitable for fusing flexible boards without additional fixtures for their holding in position during treatment nor is it capable of processing differently shaped and sized boards for a single technological cycle.